1. Field of the Invention
The present invention relates to a screen onto which an optical image from a high brightness CRT, a liquid crystal projector, or the like is projected, and to an image projection system having the screen.
2. Description of the Related Art
An image projection systems, such as a projector device, which displays images by projecting optical images using a high brightness CRT, a liquid crystal projector, or the like can simply and easily display high definition images on a large screen, and therefore has been used as information communication tool among multiple users in various ways.
A screen used in such an image projection system is devised with a technique with which beads for light diffusion are distributed across a surface of the screen to realize a wide viewing angle, to thereby provide multiple observers with improved viewability. Also, it is known to provide a directionally reflective structure, such as a lenticular lens, for the screen surface, to thereby realize a bright image area except that the viewing field angle is narrowed. Further, in JP 05-061120 A (Patent Document 1), a technique is disclosed with which directionality and isotropy are both given to the reflection characteristics of the screen by dispersing diffusion particles in the lenticular lens.
A conventional screen containing diffusion materials, such as beads, is capable of realizing a wide viewing angle, but has a dark image area due to a low gain. On the other hand, a screen using a lenticular lens has a high gain due to its high directionality, and is capable of providing a bright image area, but has a narrow viewing field angle and tends to pick up external light. Further, even when diffusion particles are dispersed in a lenticular lens, there remains a problem in that the lenticular lens tends to pick up external light. That is, it has not been possible to realize both of a screen having a wide viewing angle and a screen having high brightness on which external light has little influence at the same time.